NEW YORK (Dispatches) -- Scientists have found that
being slightly exposed to light can prompt the critical sleep-promoting hormone melatonin to plummet in preschoolers in the hour before bedtime .
University of Colorado at Boulder researchers suggest that preschoolers are highly susceptible to the physiological impacts of light at night, and some children may be even more sensitive than others.
“Our previous work showed that one, fairly high intensity of bright light before bedtime dampens melatonin levels by about 90% in young children,” said first author Lauren Hartstein, a postdoctoral fellow in the Sleep and Development Lab at CU Boulder. “With this study, we were very surprised to find high melatonin suppression across all intensities of light, even dim ones.”
Since children’s eyes have larger pupils and more transparent lenses than adults, light streams into them more freely. (One recent study showed that the transmission of blue light through a 9-year-old’s eye is 1.2-times higher than that of an adult).
Light is the body’s primary time cue, influencing circadian rhythms that regulate everything from when we feel tired or hungry to what our body temperature is throughout the day.